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		<title>three.js webgl - exporter - exr</title>
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		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> webgl - exporter - exr
		</div>

		<script type="importmap">
			{
				"imports": {
					"three": "../build/three.module.js",
					"three/addons/": "./jsm/"
				}
			}
		</script>

		<script type="module">

			import * as THREE from 'three';

			import { OrbitControls } from 'three/addons/controls/OrbitControls.js';
			import { EXRExporter, ZIP_COMPRESSION, ZIPS_COMPRESSION, NO_COMPRESSION } from 'three/addons/exporters/EXRExporter.js';
			import { RGBELoader } from 'three/addons/loaders/RGBELoader.js';
			import { GUI } from 'three/addons/libs/lil-gui.module.min.js';

			let scene, camera, renderer, exporter, mesh, controls, renderTarget, dataTexture;

			const params = {
				target: 'pmrem',
				type: 'HalfFloatType',
				compression: 'ZIP',
				export: exportFile
			};

			init();

			function init() {

				renderer = new THREE.WebGLRenderer( { antialias: true } );
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				renderer.setAnimationLoop( animate );
				document.body.appendChild( renderer.domElement );

				//

				camera = new THREE.PerspectiveCamera( 50, window.innerWidth / window.innerHeight, 0.1, 100 );
				camera.position.set( 10, 0, 0 );

				scene = new THREE.Scene();

				exporter = new EXRExporter();
				const rgbeloader = new RGBELoader();

				//

				const pmremGenerator = new THREE.PMREMGenerator( renderer );
				pmremGenerator.compileEquirectangularShader();

				rgbeloader.load( 'textures/equirectangular/san_giuseppe_bridge_2k.hdr', function ( texture ) {

					texture.mapping = THREE.EquirectangularReflectionMapping;

					renderTarget = pmremGenerator.fromEquirectangular( texture );
					scene.background = renderTarget.texture;

				} );

				createDataTexture();

				//

				controls = new OrbitControls( camera, renderer.domElement );
				controls.enableDamping = true;
				controls.rotateSpeed = - 0.25; // negative, to track mouse pointer

				//

				window.addEventListener( 'resize', onWindowResize );

				const gui = new GUI();

				const input = gui.addFolder( 'Input' );
				input.add( params, 'target' ).options( [ 'pmrem', 'data-texture' ] ).onChange( swapScene );

				const options = gui.addFolder( 'Output Options' );
				options.add( params, 'type' ).options( [ 'FloatType', 'HalfFloatType' ] );
				options.add( params, 'compression' ).options( [ 'ZIP', 'ZIPS', 'NONE' ] );

				gui.add( params, 'export' ).name( 'Export EXR' );
				gui.open();

			}

			function onWindowResize() {

				camera.aspect = window.innerWidth / window.innerHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( window.innerWidth, window.innerHeight );

			}

			function animate() {

				controls.update();
				renderer.render( scene, camera );

			}

			function createDataTexture() {

				const normal = new THREE.Vector3();
				const coord = new THREE.Vector2();
				const size = 800, radius = 320, factor = Math.PI * 0.5 / radius;
				const data = new Float32Array( 4 * size * size );

				for ( let i = 0; i < size; i ++ ) {

					for ( let j = 0; j < size; j ++ ) {

						const idx = i * size * 4 + j * 4;
						coord.set( j, i ).subScalar( size / 2 );

						if ( coord.length() < radius )
							normal.set(
								Math.sin( coord.x * factor ),
								Math.sin( coord.y * factor ),
								Math.cos( coord.x * factor )
							);
						else
							normal.set( 0, 0, 1 );

						data[ idx + 0 ] = .5 + .5 * normal.x;
						data[ idx + 1 ] = .5 + .5 * normal.y;
						data[ idx + 2 ] = .5 + .5 * normal.z;
						data[ idx + 3 ] = 1.;

					}

				}

				dataTexture = new THREE.DataTexture( data, size, size, THREE.RGBAFormat, THREE.FloatType );
				dataTexture.needsUpdate = true;

				const material = new THREE.MeshBasicMaterial( { map: dataTexture } );
				const quad = new THREE.PlaneGeometry( 50, 50 );
				mesh = new THREE.Mesh( quad, material );
				mesh.visible = false;

				scene.add( mesh );

			}

			function swapScene() {

				if ( params.target == 'pmrem' ) {

					camera.position.set( 10, 0, 0 );
					controls.enabled = true;
					scene.background = renderTarget.texture;
					mesh.visible = false;

				} else {

					camera.position.set( 0, 0, 70 );
					controls.enabled = false;
					scene.background = new THREE.Color( 0, 0, 0 );
					mesh.visible = true;

				}

			}

			async function exportFile() {

				let result, exportType, exportCompression;

				if ( params.type == 'HalfFloatType' )
					exportType = THREE.HalfFloatType;
				else
					exportType = THREE.FloatType;

				if ( params.compression == 'ZIP' )
					exportCompression = ZIP_COMPRESSION;
				else if ( params.compression == 'ZIPS' )
					exportCompression = ZIPS_COMPRESSION;
				else
					exportCompression = NO_COMPRESSION;

				if ( params.target == 'pmrem' )
					result = await exporter.parse( renderer, renderTarget, { type: exportType, compression: exportCompression } );
				else
					result = await exporter.parse( dataTexture, { type: exportType, compression: exportCompression } );

				saveArrayBuffer( result, params.target + '.exr' );

			}

			function saveArrayBuffer( buffer, filename ) {

				const blob = new Blob( [ buffer ], { type: 'image/x-exr' } );
				const link = document.createElement( 'a' );

				link.href = URL.createObjectURL( blob );
				link.download = filename;
				link.click();

			}

		</script>

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